Prevalence and patterns of third molar impaction among Ethiopians in Addis Ababa: a retrospective pilot study

Tooth impaction is a condition in which a tooth does not reach its normal position and is often observed in the third mandibular molar due to inadequate space. This study aimed to investigate the prevalence and configuration of the impacted third molars with an emphasis on angular orientations in a sample of the Ethiopian population. This cross-sectional study included a retrospective analysis of 291 patient records and orthopantomography data from the archives of a private dental clinic in Addis Ababa, during the study period from December 2020 to November 2022. Demographic details and data on the position and level of the impacted third molars were evaluated using the Winter classification. Data were analyzed for frequency distribution. The prevalence of impacted third molars was 22% (n = 64), with a greater incidence on the right side (60.9%) and a higher frequency in the mandible (67.2%). Vertical angulation (32.8%), followed by mesioangular angulation (31.2%), was the most common impaction pattern. The results highlight the need for improved treatment protocols for third molar impaction, emphasizing the prevalence in the mandible and the importance of addressing vertical impaction. Regular dental check-ups are essential for assessing third molar impaction and planning appropriate management. These data can inform policymaking and treatment considerations for impacted third molars in the Ethiopian population.


Pattern of third molar impaction
Among the 64 patients with impacted third molars, vertical impaction was the most prevalent at 32.8%, followed by mesioangular impaction at 31.2% (Table 2).www.nature.com/scientificreports/ In terms of the appearance of third molar impactions of the maxillary and mandibular, impaction of the third molar of the mandible took precedence, accounting for 67.2% of cases compared to maxillary impaction (Table 3).
There was a significantly higher incidence of third molar impaction on the right side (60.9%) than on the left side (Table 4).

Discussion
This retrospective review of the records aimed to assess the frequency and distribution of the impacted third molars among patients who sought dental care at a private dental clinic in Addis Ababa.
Third molar impaction can create significant challenges during surgery, including limited visibility and access, and an increased risk of nerve damage.Impacted molars can also cause problems, such as infection, pain, cysts, and tumors, affecting overall oral function.Regular dental checks and timely evaluation of affected molars are crucial in preventing or managing these potential problems.
This study revealed that the prevalence of affected third molars was 22%, which is consistent with the findings of a previous study conducted by Yildirim and Büyükgöze-Dindar in 2022 in Turkey 21 , where the prevalence was reported to be 23%.However, the prevalence observed in this study was lower than that reported in several other studies.For example, in a study conducted by Alfadil and Almajed Saudi Arabia in 2020 15 , 58.3% of the participants had impacted third molars, while in a study conducted by Jain et al. in 2029 in India 22 , 52.3% of orthodontic patients had at least one impacted third molar.Similarly, a study by Al-Shamahy in 2019 in Yemen 12 and a study by Al-Anqudi et al. in 2014 in Oman 23 reported prevalence rates of 38.8% and 54.3%, respectively, for individuals with at least one affected third molar.These variations may be attributed to differences in the study populations across the various studies.
In this study, the highest prevalence of third molar impaction was found at the age of 15 to 29 years, which could be because most third molars erupt at this age.In this study, the prevalence of third molar impaction was highest in females.Similarly, a study conducted by Ishwarkumar et al. in 2019 in South Africa 5 reported a higher frequency of third molar impaction in female patients.This indicates that third molar impaction is more common in women, which is related to factors such as jaw size, hormonal changes, and genetic influences that can contribute to the observed differences between men and women.
This study revealed a higher prevalence of vertical impaction (32.8%), followed closely by mesioangular impaction (31.2%).A similar trend was observed in a study conducted by Ayranci et al. in 2017 in Turkey 24 , where the vertical angulation was reported to be 57.3%, significantly surpassing that of other angulations.Similarly, a study conducted by Anjum et al. in 2014 in Pakistan indicates vertical (26%) and mesioangular (59%) impacts are the most prevalent 8 .
However, contrasting findings were observed in some studies, a study conducted by Arefi et al. in 2022 25 reveals that the most common impaction pattern was mesioangular in the mandible and distoangular in the maxilla.In a study conducted by Passi et al. in 2019 26 among the Delhi Delhi-National Capital Region population,   27 and Ramamurthy et al. in 2012 in South India 28 also highlighted mesioangular impaction as the most common pattern.The inconsistent frequency of angulation among these studies may be attributed to variations in age, ethnic and racial groups, genetics, and clinical characteristics between the investigated populations.
This study revealed a greater incidence of third molar impaction in the mandible (67.2%) than in the maxilla.This finding is consistent with previous studies, including a retrospective study by Hashemipour et al. in 2013 in southeast Iran 14 , which reported a significantly higher percentage of impacted third molars in the mandible (54.9%) than in the maxilla (28.8%).Similarly, a study conducted by Alfadil and Almajed in 2020 in Saudi Arabia 15 reveals that impaction was more common in the mandible (58.5%) than in the maxilla (41.5%).A study conducted by Chu et al. in 2003 in Hong Kong 10 also revealed that impaction of the mandibular third molars was the most prevalent (82.5%), followed by that of the maxillary third molars (15.6%).Furthermore, a study conducted by Ayranci et al. in 2017 in Turkey 24 reported a significantly higher proportion of impacted mandibular third molars (57.3%) than of impacted maxillary third molars (42.7%).The probability of impacted mandibular third molars was 1.33 times higher than that of impacted maxillary third molars.These rate variations could be attributed to factors such as different ethnic and age groups studied, eruption times, sample sizes, pathological conditions, or variations in radiographic criteria for dental development and eruption.
This study revealed that the right side (60.9%) was more affected than the left side.This finding is consistent with a retrospective study conducted by Alfadil et al. in 2020 in Saudi Arabia 15 that reported a statistically significant difference between prevalence on the right (59.9%) and left side (40.1%).Furthermore, another study conducted by Anjum et al. in 2014 in Pakistan 8 showed that impaction was more common on the right side of the mandible.Furthermore, a study conducted by Raj Kumar et al. in 2017 in Eritrea 9 showed that the right side had a higher prevalence than the left.However, in a study conducted by Chu et al. in 2003 in Hong Kong 10 , the results revealed that the distribution of the impacted teeth was similar between the left and right sides.This difference could be attributed to variations in the racial and ethnic groups of the subjects who participated in the research, as well as genetic code and sociodemographic characteristics.The findings of this study will provide evidence that clinicians should make the appropriate diagnoses and implement better treatment protocols to avoid further complications.

Strengths and limitations of the study
It is great that the study used a pre-tested instrument administered by trained data collectors, which contributed to the enhanced validity of the results.However, the limitations you have pointed out are crucial considerations for the interpretation of the study findings.

Limited generalizability:
The focus of the study on patients attending private dental clinics may limit the generalizability of the findings to the broader population.Individuals who did not visit dental clinics regularly, particularly those of lower socioeconomic status, were not included in the study.This could introduce selection bias, affecting the external validity of the results.2. Single-clinic setting: Conducting the study in a single private dental clinic may not provide a complete picture of the characteristics of third molar impaction.Dental clinic populations can vary, and results from a single clinic may not reflect the diversity present in different settings.3. Exclusion of individuals: Mentioning that a substantial number of people were not included in the study raises questions about the representativeness of the sample.Understanding the reasons for exclusion and the potential impact on the results is essential for evaluating the study's internal validity.4. Retrospective study design: The retrospective nature of the study design introduces inherent limitations, such as reliance on historical data and potential issues related to the completeness and accuracy of the data.
Readers and researchers should be aware of these constraints when considering the applicability of the findings to different populations or settings.While the study benefited from certain strengths, the limitations mentioned underscore the need for caution when generalizing the results.Future research could address these limitations by including a more diverse sample involving multiple clinics and employing a prospective study design.

Conclusions
The results of this study should be interpreted with caution in light of these limitations.The following conclusions were drawn: 1. Twenty-two percent of the patients had an affected third molar.2. There was a lower prevalence of impacted third molars in the maxilla than in the mandible.

Study area and period
The research was conducted at Dr. Emebet Special Higher Dental Clinic, located in Yeka Subcity, Addis Ababa, and founded in 1991 E.C. Recognized as one of Ethiopia's premier private dental facilities, it boasts a team of skilled professionals, including ten dentists, one dental therapist, two orthodontists, two implantologists, one radiologist, five laboratory technicians, and 24 nurses.Data were collected from December 1 to 30 December 2022.

Study design
A retrospective cross-sectional study was conducted at a private dental clinic in Addis Ababa to examine the prevalence, patterns, and factors associated with impacted third molars among patients.The investigation focused on gathering information from historical data within the institutional setting.

Population
The source population for this study included all dental patients receiving treatment at a private dental clinic.
On the other hand, the study population comprised patients who had been treated in the clinic from December 2020 to November 2022.Individuals with inadequate-quality orthopantomography, who experienced trauma, or who showed pathology in the jaw that could impact the alignment of the dentition were excluded from the study.Furthermore, patients whose third molars had no root filling were not included in the study.

Determination of the sample size
The sample size for this study was calculated using the population proportion formula, considering a confidence level of 95%, a margin of error of 5%, a prevalence of third molar impaction of 24.4% based on previous research 29 , a source population of 6000, and factoring in a nonresponse rate of 10%.As a result, the sample size determined for the study was 291 patients.

Sampling method
Study participants were selected using a systematic random sampling technique, employing a sampling interval of 20.To start the process, a random start was determined through simple random sampling, and the starting point was identified as the fourth participant.Subsequently, every 20th study participant in the sequence was included in the study.This method helped ensure a representative and unbiased sample from the larger population.

Data collection procedure
The data collection instrument for this study was developed after a meticulous review of the available literature.It was originally drafted in English and was subjected to a pre-test phase to ensure its effectiveness before being implemented in the main study.The data collection process entailed a thorough examination of patient records.Trained data collectors, supervised by designated personnel, were tasked with summarizing the information gleaned from these records.To assess the position and depth of the impacted teeth, the principal investigator conducted a panoramic radiograph analysis in collaboration with experts.The Winter classification system served as the framework to assess the location and depth of the impacted teeth.

Table 3 .
The distribution of impacted third molars between the maxilla and the mandible in Addis Ababa, 2022/23.

Table 4 .
19cation mesial angulation emerged as the most prevalent presentation in impacted mandibular third molars at 49.2%, with a vertical position observed in 24% of cases.This variation could be related to age, genetic, and clinical variations of studies.Furthermore, a study conducted by Hassan AH in 2010 in India19reported that the predominant mandibular impaction is mesioangular at 60%.Previous studies conducted by Padhye et al. in 2013 in the Indian population of third molar impaction among patients in Addis Ababa, 2022/23.Variable Frequency Percentage (%) Vol:.(1234567890)Scientific Reports | (2024) 14:8952 | https://doi.org/10.1038/s41598-024-59821-xwww.nature.com/scientificreports/